Two Space Notchers Not Fully Connected

    Keywords: Life & Death
[Diagram]

Black can live

So long as a is not occupied by White, Black can live (provided Black plays first). The vital point is at b.

[Diagram]

Black can live (correct play)

The placement at W2 won't work. After B3, a and b are miai, so the black group has two eyes.

[Diagram]

Black can live (correct play)

Black has to be careful in responding to the hane at W2. Only playing at B3 will live. Playing at a is wrong.

[Diagram]

Black can live (wrong play)

Playing at B3 is wrong. White makes a placement tesuji at W4, causing an exchange at B5, followed by connecting at W6. Black faces a shortage of liberties - being unable to play at a - and dies because the eye on top cannot be formed.

[Diagram]

Black can live (wrong play)

B1 is a very careless move. W2 is a tesuji, followed by the atari at W4 which destroys an eye in sente, and then W6 destroys another eye. Now Black is dead.

[Diagram]

Black can live (wrong play)

B1 is also wrong. White plays a placement at W2, followed by cutting at W4 in sente (aiming to capture three black stones at a), before making the final killing move at W6.

[Diagram]

Black can live (wrong play)

The descent at B1 is incorrect as well. White can kill the group with a hane at W2 (aiming to capture two black stones at a), followed by a placement at W4. B5 attempts to divide the space to make two eyes, but the connection at W6 leaves Black with a shortage of liberties, and Black cannot play at b to defend the second eye.


[Diagram]

Black is dead

The two WS stones make it impossible for the black group to live, even though it has extra liberties outside. Try figuring it yourself, using the last three diagrams in the "Black can live" section as reference. Good luck!

Dieter Verhofstadt: I refer to this particular shape in Tsumego From Games 4, so I'll work this out myself, although unkx80 left it as an exercise to the reader. I'll make it a separate page: the Flying Saucer Shape.


--unkx80


This is a copy of the living page "Two Space Notchers Not Fully Connected" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.
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